Fig 1.

Chromosomal location bias as a result of higher chromosomal copy number near the origin after ciprofloxacin treatment and the downstream effects on read counts. (A) Normal DNA replication producing two daughter cells. The origin of replication is colored purple. Multiple replication forks naturally lead to more origin (oriC) than terminus (ter) DNA. (B) Ciprofloxacin prevents DNA unwinding, stalling the replication fork. This produces a highly inflated relative concentration of DNA proximal to the origin. (C) The knock-on effects of increased DNA concentration around the origin on the read counts and fold changes, an observable peak at the origin in the relative log₂FCs and potential false positive predictions of downstream drug sensitivity testing.